The invention relates to a method for creating feed material, for example, feed for silage, a system of machines for creating feed material and a control unit for use in a system for creating feed material.
To harvest plant material intended for use as animal feed, forage harvesters are typically used that fragmentize the plant material, such as corn, beets or the like, already on the field. The chopped material obtained in this manner is transported to a silo, where it is compressed, for example, by being driven over repeatedly by a tractor. The plant material (compressed) is subsequently wrapped with an air-tight film in order to minimize contact of the plant material with atmospheric oxygen and thereby create suitable conditions for lactic fermentation. Lactic fermentation preserves the plant material and inhibits the growth of mold and other harmful organisms. Rapid processing of the plant material, which minimizes contact with atmospheric oxygen, is highly significant for the quality of the feed for silage created in this manner. Poor coordination of the processing chain, in which harvesting output is greater than compression output, results in chopped plant material in contact with atmospheric oxygen lying in a heap at the silo before it can be compressed.
In most harvesting vehicles available today, the engine is operated continuously at full output during field work, and the distribution of this output to the ground drive and chopping assembly is variable. The power requirement of the chopping assembly depends on the length of cut required for the further processing of the plant material at the silo and on the mass flow of the plant material. The mass flow of the plant material is proportional to the stand density of the plant material on the field and the ground speed of the harvesting machine. The mass throughput of the plant material in the harvesting machine is therefore not an arbitrarily controllable variable.
If the harvesting output is reduced by decreasing the number of harvesting vehicles used, it can be ensured that the chopped plant material can be compressed at the same rate at which it is delivered to the silo. Consequently, times will then occur at which the compression vehicle has nothing to do or operates unproductively, which unnecessarily increases the costs of feed production.
German patent application DE 10 2008 020 497 A1 makes known a harvesting vehicle that provides the driver with the option of varying the engine output during field work by switching between various characteristic curves. For example, in situations in which the throughput of crop is low or not present, and it is not possible or worthwhile to apply the full engine output to the ground drive (e.g., during turning maneuvers), the driver can reduce the engine output and thereby save fuel. During harvesting operation, however, the driver of such a vehicle also is required to operate as productively as possible. Operating as productively as possible might be characterized as harvesting the largest area possible in the shortest amount of time and to therefore operate the engine at the greatest useful output that is appropriate therefor.